Server switching method and apparatus, and communications system

ABSTRACT

This application provides a server switching method and apparatus, and a communications system. The method includes: receiving, by a terminal, a first notification message, where the first notification message includes an address of a second server; sending, by the terminal, to-be-sent service data to a first server and the second server based on the first notification message; receiving, by the terminal, downlink data from the first server; obtaining, by the terminal, data processing indication information; when obtaining the data processing indication information, sending, by the terminal, the to-be-sent service data to the second server; and receiving, by the terminal, downlink data from the second server. The server switching method and apparatus, and the communications system in the embodiments of this application can implement seamless switching, ensure service continuity, avoid service interruption caused when a terminal switches between servers, and help meet an end-to-end latency requirement.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of International Application No.PCT/CN2018/114494, filed on Nov. 8, 2018, which claims priority toChinese Patent Application No. 201711190960.9, filed on Nov. 24, 2017,The disclosures of the aforementioned applications are herebyincorporated by reference in their entireties.

TECHNICAL FIELD

This application relates to the communications field, and morespecifically, to a server switching method and apparatus, and acommunications system.

BACKGROUND

Ultra-reliable and low latency communications (URLLC) services areintroduced in a 5th generation (5G) communications system, and mainlyinclude services that require a low-latency and highly reliableconnection, for example, self-driving and industrial automation. Forexample, in a remote driving scenario stipulated in existing 5G TS22186,a vehicle reports image and sensing information collected by the vehicleto an application server (AS). The AS makes a driving decision (forexample, acceleration, deceleration, braking, lane changing, or normaldriving based on a current speed and lane) based on the information, anddelivers the driving decision to the vehicle to implement remote controlon the vehicle. In a remote driving service, it is required that anend-to-end latency between a vehicle and an AS be always kept at 5milliseconds (ms) to ensure service continuity.

In a current long term evolution (LTE) standard, an anycast (anycast)technology is used for switching between application services. Theanycast technology supports only stateless best effort services. In theanycast technology, when a new AS receives a first packet of servicedata sent by a vehicle, it indicates that the vehicle has beendisconnected from an original AS. However, in this case, the new AS isunable to make a driving decision yet, thereby causing substantialservice interruption. In this case, service interruption occurs when avehicle is switched between ASs by using the anycast technology.Therefore, a solution urgently needs to be proposed to ensure servicecontinuity during AS switching.

SUMMARY

This application provides a server switching method and apparatus, and acommunications system, to implement a seamless switching, therebyensuring service continuity, avoiding service interruption caused when aterminal is switched between servers, and helping meet an end-to-endlatency requirement.

According to a first aspect, a server switching method is provided. Themethod is applied to a process in which a terminal is switched from afirst server to a second server. The method includes: receiving, by theterminal, a first notification message, where the first notificationmessage includes an address of the second server; sending to-be-sentservice data to the first server and the second server based on thefirst notification message; receiving, by the terminal, downlink datafrom the first server; obtaining, by the terminal, data processingindication information; when obtaining the data processing indicationinformation, sending, by the terminal, the to-be-sent service data tothe second server; and receiving, by the terminal, downlink data fromthe second server.

By obtaining the data processing indication information, when obtainingthe data processing indication information, the terminal sends theto-be-sent service data to the second server, and receives the downlinkdata from the second server. In this way, before obtaining the dataprocessing indication information, the terminal keeps a serviceconnection to the first server, and also establishes communication withthe second service; and after obtaining the data processing indicationinformation, the terminal enables a service connection to the secondserver, to implement a seamless switching. This ensures servicecontinuity, avoids service interruption caused when the terminal isswitched between servers, and helps meet an end-to-end latencyrequirement.

In one embodiment, when obtaining the data processing indicationinformation, the terminal stops sending the to-be-sent service data tothe first server. In this way, the terminal may stop sending servicedata to the first server, thereby implementing a seamless switching ofthe terminal and reducing power consumption.

In one embodiment, when obtaining the data processing indicationinformation, the terminal sends a disconnection message to the firstserver, where the disconnection message is used to instruct the firstserver to no longer send downlink data to the terminal. In this way, theterminal instructs, by sending the disconnection message, the firstserver to no longer send downlink data, thereby reducing powerconsumption of the first server.

In another embodiment, the receiving, by the terminal, a firstnotification message includes: receiving, by the terminal, the firstnotification message from a control function entity, where the firstnotification message further includes duration of a timer; and theobtaining, by the terminal, data processing indication informationincludes: obtaining, by the terminal, the data processing indicationinformation based on the first notification message, where the dataprocessing indication information is used to indicate that the durationof the timer elapses. Therefore, by setting the timer, the terminallearns, based on the data processing indication information, that theduration of the timer elapses.

In one embodiment, the obtaining, by the terminal, data processingindication information includes: receiving, by the terminal, the dataprocessing indication information from a control function entity.Therefore, the data processing indication information may be sent by thecontrol function entity to the terminal, and an obtaining manner isrelatively flexible.

In another embodiment, the obtaining, by the terminal, data processingindication information includes: receiving, by the terminal, the dataprocessing indication information from the second server. Therefore, thedata processing indication information may be sent by the second serverto the terminal, and an obtaining manner is relatively flexible.

In one embodiment, the second server is determined by the controlfunction entity based on at least one of location information of theterminal, information about a gateway to which the terminal belongs,network information, or server load information.

According to a second aspect, a server switching method is provided. Themethod is applied to a process in which a terminal is switched from afirst server to a second server. The method includes: determining, by acontrol function entity, the second server; sending, by the controlfunction entity, a first notification message to the terminal, where thefirst notification message includes an address of the second server, andthe first notification message is used to instruct the terminal to sendto-be-sent service data to the first server and the second server; andsending, by the control function entity, data processing indicationinformation to the terminal, where the data processing indicationinformation is used to instruct the terminal to release a connection tothe first server.

The control function entity sends the data processing indicationinformation to the terminal, so that when obtaining the data processingindication information, the terminal sends the to-be-sent service datato the second server, and receives downlink data from the second server,to implement a seamless switching. This ensures service continuity,avoids service interruption caused when the terminal is switched betweenservers, and helps meet an end-to-end latency requirement.

In one embodiment, the sending, by the control function entity, dataprocessing indication information to the terminal includes: sending, bythe control function entity, the data processing indication informationto the terminal based on a second notification message from the secondserver.

In another embodiment, the sending, by the control function entity, dataprocessing indication information to the terminal includes: sending, bythe control function entity, the data processing indication informationto the terminal according to a locally configured or preconfiguredpolicy. Therefore, the control function entity may send the dataprocessing indication information to the terminal based on anotification message from the second server or according to a configuredpolicy.

In one embodiment, before the determining, by a control function entity,the second server, the method further includes: receiving, by thecontrol function entity, a trigger message from the first server, wherethe trigger message is used to instruct to perform server switching forthe terminal; and the determining, by a control function entity, thesecond server includes: determining, by the control function entity, thesecond server based on the trigger message. Therefore, the controlfunction entity may voluntarily determine a reselected server for theterminal, or may determine a reselected server for the terminal based ontriggering of the first server.

In one embodiment, the control function entity determines the secondserver based on at least one of location information of the terminal,information about a gateway to which the terminal belongs, networkinformation, or server load information.

According to a third aspect, a server switching method is provided. Themethod is applied to a process in which a terminal is switched from afirst server to a second server. The method includes: determining, by acontrol function entity, the second server; sending, by the controlfunction entity, a first notification message to the terminal, where thefirst notification message includes an address of the second server, andthe first notification message is used to instruct the terminal to sendto-be-sent service data to the first server and the second server;receiving, by the second server, the service data from the terminal; andsending, by the second server, data processing indication information tothe terminal based on a reception status of the service data, where thedata processing indication information is used to instruct the terminalto release a connection to the first server.

The control function entity determines the second server, and sends thefirst notification message to the second server. The second serverreceives the service data from the terminal, and sends the dataprocessing indication information to the terminal, where the dataprocessing indication information is used to instruct the terminal torelease the connection to the first server. This can implement aseamless switching of the terminal, thereby ensuring service continuity,avoiding service interruption caused when the terminal is switchedbetween servers, and helping meet an end-to-end latency requirement.

In one embodiment, the control function entity determines the secondserver based on at least one of location information of the terminal,information about a gateway to which the terminal belongs, networkinformation, or server load information.

According to a fourth aspect, a communications system is provided. Thecommunications system is applied to a process in which a terminal isswitched from a first server to a second server. The communicationssystem includes: a control function entity, configured to determine thesecond server, where the control function entity is further configuredto send a first notification message to the terminal, the firstnotification message includes an address of the second server, and thefirst notification message is used to instruct the terminal to sendto-be-sent service data to the first server and the second server; andthe second server, configured to receive the service data from theterminal, where the second server is further configured to send a secondnotification message to the control function entity based on a receptionstatus of the service data, the control function entity is furtherconfigured to send data processing indication information to theterminal based on the second notification message, the data processingindication information is used to instruct the terminal to release aconnection to the first server, and the second server is furtherconfigured to send downlink data to the terminal.

In the communications system in this embodiment of this application, thecontrol function entity determines the second server, and sends thefirst notification message to the second server; and the second serverreceives the service data from the terminal, and sends the secondnotification message to the control function entity, so that the controlfunction entity sends the data processing indication information to theterminal based on the second notification message, where the dataprocessing indication information is used to instruct the terminal torelease the connection to the first server. This can implement aseamless switching of the terminal, thereby ensuring service continuity,avoiding service interruption caused when the terminal is switchedbetween servers, and helping meet an end-to-end latency requirement.

In one embodiment, before determining the second server, the controlfunction entity is further configured to: receive a trigger message fromthe first server, where the trigger message is used to instruct thecontrol function entity to perform server switching for the terminal;and determine the second server based on the trigger message. Therefore,the control function entity may voluntarily determine a reselectedserver for the terminal, or may determine a reselected server for theterminal based on triggering of the first server.

In one embodiment, the control function entity determines the secondserver based on at least one of location information of the terminal,information about a gateway to which the terminal belongs, networkinformation, or server load information.

According to a fifth aspect, a communications system is provided. Thecommunications system is applied to a process in which a terminal isswitched from a first server to a second server. The communicationssystem includes: a control function entity, configured to determine thesecond server, where the control function entity is further configuredto send a first notification message to the terminal, the firstnotification message includes an address of the second server, and thefirst notification message is used to instruct the terminal to sendto-be-sent service data to the first server and the second server; andthe second server, configured to receive the service data from theterminal, where the second server is further configured to send dataprocessing indication information to the terminal based on a receptionstatus of the service data, and the data processing indicationinformation is used to instruct the terminal to release a connection tothe first server.

The control function entity determines the second server, and sends thefirst notification message to the second server. The second serverreceives the service data from the terminal, and sends the dataprocessing indication information to the terminal, where the dataprocessing indication information is used to instruct the terminal torelease the connection to the first server. This can implement aseamless switching of the terminal, thereby ensuring service continuity,avoiding service interruption caused when the terminal is switchedbetween servers, and helping meet an end-to-end latency requirement.

In one embodiment, the control function entity determines the secondserver based on at least one of location information of the terminal,information about a gateway to which the terminal belongs, networkinformation, or server load information.

According to a sixth aspect, a server switching apparatus is provided,configured to perform the method on the control function entity side inany one of the foregoing aspects or the possible implementations of theforegoing aspects. Specifically, the apparatus includes a moduleconfigured to perform the method on the control function entity side inany one of the foregoing aspects or the possible implementations of theforegoing aspects.

According to a seventh aspect, a server switching apparatus is provided,configured to perform the method on the second server side in any one ofthe foregoing aspects or the possible implementations of the foregoingaspects. Specifically, the apparatus includes a module configured toperform the method on the second server side in any one of the foregoingaspects or the possible implementations of the foregoing aspects.

According to an eighth aspect, an apparatus is provided, configured toperform the method according to any one of the first aspect or thepossible implementations of the first aspect. Specifically, theapparatus includes a module configured to perform the method in any oneof the first aspect or the possible implementations of the first aspect.The apparatus may be a terminal, or may be a chip.

According to a ninth aspect, a server switching apparatus is provided.The apparatus includes a processor, a memory, and a transceiver. Theprocessor is connected to the memory and the transceiver. The memory isconfigured to store an instruction, the processor is configured toexecute the instruction, and the transceiver is configured tocommunicate with another network element under control of the processor.When the processor executes the instruction stored in the memory, theexecution enables the apparatus to perform the method on the controlfunction entity side in any one of the foregoing aspects or the possibleimplementations of the foregoing aspects.

According to a tenth aspect, a server switching apparatus is provided.The apparatus includes a processor, a memory, and a transceiver. Theprocessor is connected to the memory and the transceiver. The memory isconfigured to store an instruction, the processor is configured toexecute the instruction, and the transceiver is configured tocommunicate with another network element under control of the processor.When the processor executes the instruction stored in the memory, theexecution enables the apparatus to perform the method on the secondserver side in any one of the foregoing aspects or the possibleimplementations of the foregoing aspects.

According to an eleventh aspect, an apparatus is provided. The apparatusincludes a processor, a memory, and a transceiver. The processor isconnected to the memory and the transceiver. The memory is configured tostore an instruction, the processor is configured to execute theinstruction, and the transceiver is configured to communicate withanother network element under control of the processor. When theprocessor executes the instruction stored in the memory, the executionenables the apparatus to perform the method in any one of the firstaspect or the possible implementations of the first aspect. Theapparatus may be a terminal, or may be a chip.

According to a twelfth aspect, a computer readable storage medium isprovided. The computer readable storage medium stores a program. Theprogram enables a control function entity to perform the method on thecontrol function entity side in any one of the foregoing aspects or thepossible implementations of the foregoing aspects.

According to a thirteenth aspect, a computer readable storage medium isprovided. The computer readable storage medium stores a program. Theprogram enables a second server to perform the method on the secondserver side in any one of the foregoing aspects or the possibleimplementations of the foregoing aspects.

According to a fourteenth aspect, a computer readable storage medium isprovided. The computer readable storage medium stores a program. Theprogram enables a terminal to perform the server switching method in anyone of the first aspect or the implementations of the first aspect.

According to a fifteenth aspect, a communications chip is provided. Thecommunications chip stores an instruction. When the instruction runs ona computer device, the communications chip is enabled to perform themethod in any one of the possible implementations of the foregoingaspects.

According to a sixteenth aspect, a computer program product including aninstruction is provided. When the instruction runs on a computer, thecomputer is enabled to perform the method in any one of the foregoingaspects or the possible implementations of the foregoing aspects.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a schematic architectural diagram of a system to which anembodiment of this application is applied;

FIG. 2 is a diagram of a scenario to which an embodiment of thisapplication is applied;

FIG. 3 is a schematic block diagram of a computer device to which anembodiment of this application is applied;

FIG. 4 is a schematic flowchart of a server switching method accordingto an embodiment of this application;

FIG. 5 is a schematic flowchart of a server switching method accordingto another embodiment of this application;

FIG. 6 is a schematic flowchart of a server switching method accordingto still another embodiment of this application;

FIG. 7 is a schematic flowchart of a server switching method accordingto yet another embodiment of this application;

FIG. 8 is a schematic structural diagram of a server switching apparatusaccording to an embodiment of this application;

FIG. 9 is a schematic structural diagram of a server switching apparatusaccording to another embodiment of this application; and

FIG. 10 is a schematic structural diagram of a server switchingapparatus according to still another embodiment of this application.

DESCRIPTION OF EMBODIMENTS

The following describes technical solutions of this application withreference to accompanying drawings.

The technical solutions in the embodiments of this application may beapplied to various communications systems, for example, a global systemfor mobile communications (GSM) system, a code division multiple access(CDMA) system, a wideband code division multiple access (WCDMA) system,a general packet radio service (GPRS) system, a long term evolution(LTE) system, an LTE frequency division duplex (FDD) system, an LTE timedivision duplex (TDD) system, a universal mobile telecommunicationssystem (UMTS), a worldwide interoperability for microwave access (WiMAX)communications system, a future 5th generation (5G) system, anothersystem in the future, a new radio (NR) system, and avehicle-to-everything (V2X) internet of vehicles system.

FIG. 1 is a schematic architectural diagram of a system to which anembodiment of this application is applied. As shown in FIG. 1, thesystem 100 includes a second server 110 and a control function entity120. In one embodiment, the system 100 further includes a terminal 140and a first server 130. In one embodiment, the terminal 140 may beswitched from the first server 130 to the second server 110.

The system 100 may be configured to perform a server switching method inan embodiment of this application.

In one embodiment, the system 100 is applied to a process in which theterminal 140 is switched from the first server 130 to the second server110, and specifically includes: the control function entity 120,configured to determine the second server 110, where the controlfunction entity 120 is further configured to send a first notificationmessage to the terminal 140, the first notification message includes anaddress of the second server 110, and the first notification message isused to instruct the terminal 140 to send to-be-sent service data to thefirst server 130 and the second server 110; and the second server 110,configured to receive the service data from the terminal 140, where thesecond server 110 is further configured to send a second notificationmessage to the control function entity 120 based on a reception statusof the service data, the control function entity 120 is furtherconfigured to send data processing indication information to theterminal 140 based on the second notification message, the dataprocessing indication information is used to instruct the terminal 140to release a connection to the first server 130, and the second server110 is further configured to send downlink data to the terminal 140.Therefore, in the system 100, the second server receives the servicedata from the terminal, and sends the second notification message to thecontrol function entity, so that the control function entity sends thedata processing indication information to the terminal based on thesecond notification message, where the data processing indicationinformation is used to instruct the terminal to release the connectionto the first server. This can implement a seamless switching of theterminal, thereby ensuring service continuity, avoiding serviceinterruption caused when the terminal is switched between servers, andhelping meet an end-to-end latency requirement.

In another embodiment, the system 100 specifically includes: the controlfunction entity 120, configured to determine the second server 110,where the control function entity 120 is further configured to send afirst notification message to the terminal 140, the first notificationmessage includes an address of the second server 110, and the firstnotification message is used to instruct the terminal 140 to sendto-be-sent service data to the first server 130 and the second server110; and the second server 110, configured to receive the service datafrom the terminal 140, where the second server 110 is further configuredto send data processing indication information to the terminal 140 basedon a reception status of the service data, and the data processingindication information is used to instruct the terminal 140 to release aconnection to the first server 130. Therefore, in the system 100, thesecond server receives the service data from the terminal, and directlysends the data processing indication information to the terminal basedon the reception status of the service data, where the data processingindication information is used to instruct the terminal to release theconnection to the first server. This can implement a seamless switchingof the terminal, thereby ensuring service continuity, avoiding serviceinterruption caused when the terminal is switched between servers, andhelping meet an end-to-end latency requirement.

In one embodiment, the second server 110 and the control function entity120 in FIG. 1 may be implemented by one entity device, or may be jointlyimplemented by a plurality of entity devices, or may be one logicalfunction module in one entity device. This is not limited in thisembodiment of this application.

It should be noted that the control function entity, the first server,the second server, and the like in FIG. 1 are merely names, and thenames do not constitute a limitation on the devices. In a 5G network oranother network in the future, network elements or entitiescorresponding to a control function entity, a second server, and a firstserver may have other names. This is not specifically limited in thisembodiment of this application. For example, the control function entitymay be alternatively replaced with a V2X control function entity or acloud AS entity. A collective description is provided herein, anddetails are not repeated below.

In one embodiment, in actual deployment, the control function entity 120and the second server 110 in the system 100 may belong to a sameoperator, or may be deployed separately. This is not limited in thisembodiment of this application.

In one embodiment, the control function entity 120 and the second server110 in the system 100 may exist in a form of an entity, or may beimplemented in a form of a software module. This is not limited in thisembodiment of this application.

The terminal in the embodiments of this application may be userequipment, an access terminal, a terminal in V2X communication, a userunit, a user station, a mobile station, a mobile station, a remotestation, a remote terminal, a mobile device, a user terminal, a terminaldevice, a wireless communications device, a user agent, or a userapparatus. The terminal may alternatively be a cellular phone, acordless phone, a session initiation protocol (SIP) phone, a wirelesslocal loop (WLL) station, a personal digital assistant (PDA), a handhelddevice having a wireless communication function, a computing device,another processing device connected to a wireless modem, avehicle-mounted device, a wearable device, a terminal device in a future5G network, a terminal device in a future evolved public land mobilenetwork (PLMN), or the like. This is not limited in the embodiments ofthis application. The terminal may alternatively be a V2X device, forexample, a vehicle or an on-board unit (OBU) in a vehicle.

The terminal in the embodiments of this application is connected to aradio access network (RAN) device in a wireless manner, and the radioaccess network device is connected to a core network device (not shownin FIG. 1) in a wireless or wired manner. The core network device andthe radio access network device may be different separate physicaldevices, or a function of the core network device and a logical functionof the radio access network device may be integrated to one physicaldevice, or some functions of the core network device and some functionsof the radio access network device may be integrated to one physicaldevice. The terminal may be in a fixed location, or may be mobile.

The radio access network device is an access device used by the terminalto access the mobile communications system in a wireless manner; and maybe a NodeB NodeB, an evolved NodeB eNodeB, a gNB gNB in a 5G mobilecommunications system, a base station in a future mobile communicationssystem, an access node in a Wi-Fi system, or the like, or may be a radiocontroller in a cloud radio access network (CRAN) scenario.Alternatively, the access network device may be a relay station, anaccess point, a vehicle-mounted device, a wearable device, a networkdevice in a future 5G network, a network device in a future evolved PLMNnetwork, or the like. A specific technology and a specific device formused for the radio access network device are not limited in theembodiments of this application.

The core network device includes, for example, a mobility managemententity (MME) or a broadcast multicast service center (BMSC); or mayinclude a corresponding function entity in a 5G NR system, for example,a core network control plane (CP) or user plane (UP) function, forexample, a session management function (SMF) or an access and mobilitymanagement function (AMF). A core network control plane may also beunderstood as a core network control plane function (CPF) entity.

V2X communication means that a vehicle may obtain road conditioninformation or receive information in a timely manner throughvehicle-to-vehicle (V2V) communication, vehicle-to-infrastructure (V2I)communication, vehicle-to-pedestrian (V2P) communication,vehicle-to-network (V2N) communication, or the like. Using the mostcommon V2V and V2I as examples, a vehicle may broadcast, to a nearbyvehicle through V2V communication, information about the vehicle, forexample, a driving speed, a driving direction, a specific location, orwhether emergency braking is performed; and the nearby vehicle obtainsthe information, so that a driver may better sense a traffic condition,to pre-determine a dangerous situation to avoid the situation in atimely manner. In one embodiment, for the V2I communication, in additionto exchange of the foregoing safety information, roadside infrastructuremay further provide a vehicle with various types of service information,data network access, and the like. Functions such as non-stop tollcollection and in-vehicle entertainment greatly improve trafficintelligence. Generally, a network used for V2X communication isreferred to as an internet of vehicles.

The radio access network device and the terminal may be deployed onland, including an indoor, outdoor, handheld, or vehicle-mountedscenario; or may be deployed on water; or may be deployed on anairplane, a balloon, or a satellite in the air. Application scenarios ofthe radio access network device and the terminal are not limited in theembodiments of this application.

The embodiments of this application are applicable to downlink signaltransmission, or is applicable to uplink signal transmission, or isapplicable to device-to-device (D2D) signal transmission. For thedownlink signal transmission, a sending device is a radio access networkdevice, and a corresponding receiving device is a terminal. For theuplink signal transmission, a sending device is a terminal, and acorresponding receiving device is a radio access network device. For theD2D signal transmission, a sending device is a terminal, and acorresponding receiving device is also a terminal. A signal transmissiondirection is not limited in the embodiments of this application.

Communication between the radio access network device and the terminaland between the terminals may be performed by using a licensed spectrum(licensed spectrum), or communication may be performed by using anunlicensed spectrum (unlicensed spectrum), or communication may beperformed by using both a licensed spectrum and an unlicensed spectrum.Communication between the radio access network device and the terminaland between the terminals may be performed by using a spectrum below 6Gigahertz (GHz), or communication may be performed by using a spectrumabove 6 GHz, or communication may be performed by using both a spectrumbelow 6 GHz and a spectrum above 6 GHz. A spectrum resource used betweenthe radio access network device and the terminal is not limited in thisembodiment of this application.

In one embodiment, the system 100 shown in FIG. 1 may be applied to a 5Gnetwork or another possible network in the future. This is notspecifically limited in this embodiment of this application.

When the system 100 shown in FIG. 1 is applied to the 5G network, asshown in FIG. 2, for example, the control function entity 120 may be aV2X control function entity or a cloud AS in 5G, and the first server130 or the second server 110 may be a local AS.

FIG. 2 is a diagram of a scenario to which an embodiment of thisapplication is applied. As shown in FIG. 2, system 200 includes a localapplication server (AS) and a V2X control function entity. In oneembodiment, the system 200 may further include a terminal and a cloudAS. The cloud AS may exist or not exist. An application server AScommunicates with the terminal through a network. For a low-latencyservice, the local AS is used for the terminal. The cloud AS may providethe terminal with information such as traffic road condition, and mayfurther notify the terminal of an address of the local AS. The V2Xcontrol function entity is responsible for authenticating the terminal.In one embodiment, the V2X control function entity may further notifythe terminal of an address of the AS.

It should be noted that the V2X control function entity, the local AS,the cloud AS, and the like in FIG. 2 are merely names, and the names donot constitute a limitation on the devices. In a 5G network or anothernetwork in the future, network elements or entities corresponding to theV2X control function entity, the local AS, and the cloud AS may haveother names. This is not specifically limited in this embodiment of thisapplication. For example, the V2X control function entity may bealternatively replaced with a V2X control function or a cloud AS. Acollective description is provided herein, and details are not repeatedbelow.

FIG. 3 is a schematic block diagram of a computer device 300 (or aserver switching apparatus) to which an embodiment of this applicationis applied. The second server 110, the control function entity 120, thefirst server 130, or the terminal 140 in FIG. 1 may be implemented bythe computer device in FIG. 3. Alternatively, the terminal, the localAS, the cloud AS, or the V2X control function entity in FIG. 2 may beimplemented by the computer device in FIG. 3.

As shown in FIG. 3, the computer device includes a processor 301, amemory 302, and a transceiver 303.

The processor 301, the memory 302, and the transceiver 303 communicatewith each other through an internal connection, to transfer controland/or data signals.

It may be understood that, although not shown, the computer device 300may further include another apparatus, such as an input apparatus, anoutput apparatus, or a battery.

In one embodiment, in some embodiments, the memory 302 may store anexecutable instruction used for performing a method in an embodiment ofthis application. The processor 301 may execute the instruction storedin the memory 302 and cooperate with other hardware (for example, thetransceiver 303), to perform operations in the following method. For aspecific working process and beneficial effects, refer to descriptionsin the following method embodiment.

The method disclosed in the embodiments of this application may beapplied to a processor or may be implemented by a processor. Theprocessor may be an integrated circuit chip and has a signal processingcapability. In an implementation process, operations in the foregoingmethods can be implemented by using a hardware integrated logicalcircuit in the processor, or by using instructions in a form ofsoftware. The processor may be a general-purpose processor, a digitalsignal processor (DSP), an application-specific integrated circuit(ASIC), a field programmable gate array (FPGA) or another programmablelogic device, a discrete gate or transistor logic device, or a discretehardware component. The processor may implement or perform the methods,the operations, and logical block diagrams that are disclosed in theembodiments of this application. The general-purpose processor may be amicroprocessor, or the processor may be any conventional processor orthe like. Operations of the methods disclosed with reference to theembodiments of this application may be directly executed andaccomplished by using a hardware decoding processor, or may be executedand accomplished by using a combination of hardware and software modulesin the decoding processor. A software module may be located in a maturestorage medium in the art, such as a random access memory (RAM), a flashmemory, a read-only memory (ROM), a programmable read-only memory, anelectrically erasable programmable memory, or a register. The storagemedium is located in the memory, and a processor reads instructions inthe memory and completes the operations in the foregoing methods incombination with hardware of the processor.

The computer device 300 may be a general-purpose computer device or adedicated computer device. During specific implementation, the computerdevice 300 may be a desktop computer, a portable computer, a networkserver, a palmtop computer (PDA), a mobile phone, a tablet computer, awireless terminal device, a communications device, an embedded device,or a device with a structure similar to that in FIG. 3. A type of thecomputer device 300 is not limited in this embodiment of thisapplication.

FIG. 4 is a schematic flowchart of a server switching method accordingto an embodiment of this application. This embodiment of thisapplication may be applied to an internet of vehicles scenario.Specifically, the method is applied to a process in which a terminal isswitched from a first server to a second server. In one embodiment, inthis embodiment of this application, a server may be an AS, and acontrol function entity may be a V2X CF or a cloud AS. As shown in FIG.4, the method includes the following operations.

Operation 401: The terminal receives a first notification message, wherethe first notification message includes an address of the second server.

In one embodiment, the first notification message may be sent by thecontrol function entity.

Operation 402: The terminal sends to-be-sent service data to the firstserver and the second server based on the first notification message.

In one embodiment, the terminal may replicate the to-be-sent servicedata and send copies to the first server and the second serverrespectively.

Operation 403: The first server sends downlink data to the terminal.Correspondingly, the terminal receives the downlink data from the firstserver.

Herein, the terminal uses the downlink data sent by the first server.Even if the terminal receives downlink data sent by the second server,the terminal caches or discards the downlink data sent by the secondserver, without using the downlink data sent by the second server.

Operation 404: The terminal obtains data processing indicationinformation.

In one embodiment, the data processing indication information may besent by the control function entity, or may be sent by the secondserver, or may be determined by the terminal based on duration of atimer.

Operation 405: When obtaining the data processing indicationinformation, the terminal sends the to-be-sent service data to thesecond server.

A difference from operation 402 lies in that the terminal no longersends the service data to both the first server and the second server,but sends the service data only to the second server.

It should be noted that the to-be-sent service data in operation 402 andthe to-be-sent service data in operation 405 are different service data.

Herein, the second server has learned sufficient information about theterminal, is capable of controlling the terminal, and can take over theterminal.

Operation 406: The second server sends downlink data to the terminal.Correspondingly, the terminal receives the downlink data from the secondserver.

A difference between operation 406 and operation 403 lies in that, inoperation 406, the terminal uses the downlink data sent by the secondserver.

Therefore, in the server switching method in this embodiment of thisapplication, by obtaining the data processing indication information,when obtaining the data processing indication information, the terminalsends the to-be-sent service data to the second server, and receives thedownlink data from the second server. In this way, before obtaining thedata processing indication information, the terminal keeps a serviceconnection to the first server, and also establishes communication withthe second service; and after obtaining the data processing indicationinformation, the terminal enables a service connection to the secondserver, to implement a seamless switching. This ensures servicecontinuity, avoids service interruption caused when a terminal isswitched between servers, and helps meet an end-to-end latencyrequirement.

In one embodiment, when obtaining the data processing indicationinformation, the terminal stops sending the to-be-sent service data tothe first server.

Specifically, when or after obtaining the data processing indicationinformation, the terminal stops sending the to-be-sent service data tothe first server. Further, the terminal sends the to-be-sent servicedata to the second server, and the second server takes over a servicefor the terminal, that is, the terminal releases a service connection tothe first server and enables a service connection to the second server.

Alternatively, in one embodiment, when obtaining the data processingindication information, the terminal sends a disconnection message tothe first server, where the disconnection message is used to instructthe first server to no longer send downlink data to the terminal.

Specifically, when or after obtaining the data processing indicationinformation, the terminal sends the disconnection message to the firstserver, so that the first server no longer sends downlink data to theterminal. Further, the terminal sends the to-be-sent service data to thesecond server, and the second server takes over a service for theterminal, that is, the terminal releases a service connection to thefirst server and enables a service connection to the second server.

In this embodiment of this application, the terminal may obtain the dataprocessing indication information in a plurality of manners. Thefollowing provides respective descriptions.

Manner 1: Operation 401 includes: The terminal receives the firstnotification message from the control function entity, where the firstnotification message further includes the duration of the timer.

Correspondingly, operation 404 includes: The terminal obtains the dataprocessing indication information based on the first notificationmessage, where the data processing indication information is used toindicate that the duration of the timer elapses.

Specifically, the control function entity sends the first notificationmessage to the terminal, where the first notification message mayfurther include the duration of the timer; and after the duration of thetimer elapses, the terminal sends the to-be-sent service data to thesecond server.

Manner 2: Operation 404 includes: The terminal receives the dataprocessing indication information from the control function entity.

For example, the control function entity sends the data processingindication information to the terminal when the second server notifiesthe control function entity that the second server is capable ofcontrolling the terminal or is properly controlling the terminal, orwhen a data amount of uplink data on the second server that comes fromthe terminal has satisfied a predefined condition.

Manner 3: Operation 404 includes: The terminal receives the dataprocessing indication information from the second server.

For example, the second server directly sends the data processingindication information to the terminal when the second server is capableof controlling the terminal or is properly controlling the terminal, orwhen a data amount of uplink data on the second server that comes fromthe terminal has satisfied a predefined condition.

To sum up, the data processing indication information obtained by theterminal may come from different channels. It should be understood thatthe foregoing three manners are used only as an example for descriptionherein, and do not constitute a limitation on this embodiment of thisapplication.

With reference to FIG. 5, the following describes a server switchingmethod according to another embodiment of this application. It should beunderstood that operations or concepts similar to those in FIG. 4 arenot described again. FIG. 5 is a schematic flowchart of a serverswitching method according to another embodiment of this application.This embodiment of this application may be applied to an internet ofvehicles scenario. Specifically, the method is applied to a process inwhich a terminal is switched from a first server to a second server. Inone embodiment, in this embodiment of this application, a server may bean AS, and a control function entity may be a V2X CF or a cloud AS. Itshould be noted that a dashed line before operation 501 indicates thatthe terminal has established communication with the first server. Asshown in FIG. 5, the method includes the following operations.

Operation 501: The control function entity determines the second server.

In one embodiment, the control function entity may determine the secondserver based on at least one of location information of the terminal,information about a gateway to which the terminal belongs, networkinformation, or server load information. The gateway to which theterminal belongs may be a control plane CP gateway, or may be a userplane UPF gateway. The server load information may include loadinformation of the first server and/or load information of the secondserver.

Specifically, the control function entity reselects a server for theterminal, and selects the second server as a server to which theterminal is to be switched. A server may be reselected based on at leastone of the following factors:

(1) A network side (a specific network element may be an SW node or anAMF node) notifies the control function entity of at least one of alocation of the gateway to which the terminal belongs, a location of theterminal, and an address of the terminal. Correspondingly, the controlfunction entity determines, based on the address of the terminal, thefirst server that is currently in a communication connection to theterminal, and reselects the second server for the terminal based on thelocation of the gateway to which the terminal belongs, a location of anew gateway to which the terminal belongs after the terminal moves, anda location of the terminal after the terminal moves.

(2) When the first server is overloaded or is faulty, the first serversends a trigger message to the control function entity, where thetrigger message is used to instruct the control function entity toperform server switching for the terminal. Correspondingly, the controlfunction entity reselects the second server for the terminal based onthe trigger message from the first server.

Operation 502: The control function entity sends a server switchingmessage to the first server, where the server switching message carriesinformation such as an address of the second server and the address ofthe terminal. Correspondingly, the first server receives the serverswitching message.

Operation 503: The first server sends service authentication informationto the second server based on the server switching message.

Specifically, the first server finds context information of the terminalbased on the address of the terminal. The context information of theterminal is locally stored on the first server. The context informationincludes the service authentication information and the like. The firstserver sends the information to the second server, so that the secondserver prepares for taking over a service for the terminal.

Operation 504: The second server sends a switching acknowledgement tothe control function entity. Correspondingly, the control functionentity receives the switching acknowledgement.

Specifically, the second server establishes a context of the terminalbased on the service authentication information, synchronizes data withthe first server, and sends the switching acknowledgement to the controlfunction entity. The switching acknowledgement is used to notify thecontrol function entity that the second server is ready to take over theservice for the terminal.

Operation 505: The control function entity sends a first notificationmessage to the terminal, where the first notification message includesthe address of the second server, and the first notification message isused to instruct the terminal to send to-be-sent service data to thefirst server and the second server. Correspondingly, the terminalreceives the first notification message.

In one embodiment, in operation 505, the first notification message mayfurther include duration of a timer. The control function entitydetermines the duration of the timer based on at least one of thefollowing factors:

(1) A service requirement of the terminal. For example, for a remotedriving service, a vehicle is not allowed to lose control, that is,there needs to always be an available server that can control thevehicle. For this service, a timer setting principle is that theterminal is allowed to release a connection to the first server onlyafter the second server has learned sufficient data and is capable ofcontrolling the terminal. For example, the timer is set to 10s.

(2) A static configuration. For example, local configuration isperformed on the control function entity. To be specific, a serviceprovider configures the duration of the timer on the control functionentity based on a service attribute, so that the control function entitydirectly obtains the duration of the timer locally and delivers theduration of the timer to the terminal.

In one embodiment, the terminal obtains data processing indicationinformation based on the duration of the timer, where the dataprocessing indication information is used to indicate that the durationof the timer elapses.

Alternatively, the first notification message may not carry duration ofa timer, and the control function entity directly sends data processingindication information to the terminal.

Operation 506: The terminal establishes service communication with thesecond server based on the address of the second server.

Specifically, when receiving the first notification message, theterminal simultaneously sends uplink data to the first server and thesecond server. For downlink data, the terminal uses downlink data sentby the first server, and caches or discards downlink data sent by thesecond server. In other words, in this case, although the terminal hasestablished communication with both the first server and the secondserver, the terminal uses the downlink data sent by the first server.

Herein, after obtaining the duration of the timer, the terminal maystart the timer, and perform operation 507 when the timer expires.

Operation 507: The terminal starts to use the second server when thetimer expires.

The terminal obtains the data processing indication information based onthe duration of the timer included in the first notification message,where the data processing indication information is used to indicatethat the duration of the timer elapses. In this case, the terminalreleases the connection to the first server, starts to use the secondserver, and uses the downlink data sent by the second server.

In one embodiment, the terminal may not immediately stop using the firstserver, so that the terminal can fall back to the first server when thesecond server becomes faulty, thereby ensuring stability of acommunications system. This is not limited in this embodiment of thisapplication.

In one embodiment, the first notification message may alternatively notinclude duration of a timer. In one embodiment, the data processingindication information obtained by the terminal may be sent by thecontrol function entity. The following provides descriptions withreference to a flowchart in FIG. 6. In one embodiment, a process in FIG.6 may be performed by the system 100 in FIG. 1 or the system 200 in FIG.2. This is not limited in this embodiment of this application. Operation601 to operation 606 in FIG. 6 are similar to operation 501 to operation506 in FIG. 5. Refer to the foregoing descriptions. For brevity, detailsare not described herein again. In operation 605 in FIG. 6, the firstnotification message does not include duration of a timer. It should benoted that a dashed line before operation 601 indicates that theterminal has established communication with the first server. As shownin FIG. 6, the method further includes the following operations.

Operation 607: The second server sends a second notification message tothe control function entity based on a reception status of the servicedata. Correspondingly, the control function entity receives the secondnotification message from the second server, where the secondnotification message indicates that the second server is ready to takeover a service for the terminal.

Specifically, the second server has learned sufficient service data, forexample, can make a control decision based on data at a current momentand data in last 2 seconds. In this case, the second server sends thesecond notification message to the control function entity.

Operation 608: The control function entity sends data processingindication information to the terminal, where the data processingindication information is used to instruct the terminal to release aconnection to the first server. Correspondingly, the terminal receivesthe data processing indication information from the control functionentity.

In one embodiment, operation 608 includes: The control function entitymay send the data processing indication information to the terminalbased on the second notification message; or in one embodiment, thecontrol function entity may send the data processing indicationinformation to the terminal according to a locally configured orpreconfigured policy; or the control function entity sends the dataprocessing indication information to the terminal after a transitiontime elapses, for example, after the transition time elapses, an amountof data on the second server satisfies a predefined condition.

In one embodiment, the data processing indication information may bealternatively used to indicate that the second server is capable oftaking over the terminal, that is, is capable of controlling theterminal.

Operation 609: The terminal starts to use the second server.

In one embodiment, in this case, the terminal releases the connection tothe first server, starts to use the second server, and uses downlinkdata sent by the second server. Alternatively, in one embodiment, theterminal may not immediately stop using the first server, so that theterminal can fall back to the first server when the second serverbecomes faulty, thereby ensuring stability of a communications system.This is not limited in this embodiment of this application.

In this embodiment of this application, the control function entitysends the data processing indication information to the terminal, sothat when obtaining the data processing indication information, theterminal sends the to-be-sent service data to the second server, andreceives the downlink data from the second server, to implement aseamless switching. This ensures service continuity, avoids serviceinterruption caused when the terminal is switched between servers, andhelps meet an end-to-end latency requirement.

In one embodiment, the data processing indication information obtainedby the terminal may be sent by the second server. The following providesdescriptions with reference to a flowchart in FIG. 7. In one embodiment,a process in FIG. 7 may be performed by the system 100 in FIG. 1 or thesystem 200 in FIG. 2. This is not limited in this embodiment of thisapplication. Operation 701 to operation 706 in FIG. 7 are similar tooperation 501 to operation 506 in FIG. 5. Refer to the foregoingdescriptions. For brevity, details are not described herein again. Inoperation 705 in FIG. 7, the first notification message does not includeduration of a timer. It should be noted that a dashed line beforeoperation 701 indicates that the terminal has established communicationwith the first server. As shown in FIG. 7, the method further includesthe following operations.

Operation 707: The second server sends data processing indicationinformation to the terminal, where the data processing indicationinformation is used to instruct the terminal to release a connection tothe first server. Correspondingly, the terminal receives the dataprocessing indication information from the second server.

Specifically, the second server may send the data processing indicationinformation to the terminal based on a reception status of the servicedata or after an amount of uplink data received from the terminalsatisfies a predefined condition.

In one embodiment, the data processing indication information may bealternatively used to indicate that the second server is capable oftaking over the terminal, that is, is capable of controlling theterminal.

Operation 708: The terminal starts to use the second server.

In one embodiment, in this case, the terminal releases the connection tothe first server, starts to use the second server, and uses downlinkdata sent by the second server. Alternatively, in one embodiment, theterminal may not immediately stop using the first server, so that theterminal can fall back to the first server when the second serverbecomes faulty, thereby ensuring stability of a communications system.This is not limited in this embodiment of this application.

In this embodiment of this application, the second server sends the dataprocessing indication information to the terminal, so that whenobtaining the data processing indication information, the terminal sendsthe to-be-sent service data to the second server, and receives thedownlink data from the second server, to implement a seamless switching.This ensures service continuity, avoids service interruption caused whenthe terminal is switched between servers, and helps meet an end-to-endlatency requirement.

It should be understood that, the examples in FIG. 4 to FIG. 7 are onlyfor ease of understanding the embodiments by a person skilled in theart, and are not intended to limit the embodiments of this applicationto a specific scenario in the examples. Definitely, a person skilled inthe art can make various equivalent modifications or changes based onthe examples shown in FIG. 4 to FIG. 7, and such modifications orchanges also fall within the scope of the embodiments of thisapplication.

The foregoing describes the server switching method according to theembodiments of this application. The following describes an apparatusaccording to an embodiment of this application.

FIG. 8 is a schematic structural diagram of a server switching apparatus800 according to an embodiment of this application. In one embodiment, aspecific form of the apparatus 800 may be a general-purpose computerdevice or a chip in the general-purpose computer device. This is notlimited in this embodiment of this application. The apparatus 800 isapplied to a process in which a terminal is switched from a first serverto a second server. The apparatus 800 is a control function entity, andthe control function entity includes:

a determining module 810, configured to determine the second server; and

a transceiver module 820, configured to send a first notificationmessage to the terminal, where the first notification message includesan address of the second server, and the first notification message isused to instruct the terminal to send to-be-sent service data to thefirst server and the second server; where

the transceiver module 820 is further configured to send data processingindication information to the terminal, and the data processingindication information is used to instruct the terminal to release aconnection to the first server.

In one embodiment, that the transceiver module 820 is configured to sendthe data processing indication information to the terminal specificallyincludes: sending the data processing indication information to theterminal based on a second notification message from the second server.

In one embodiment, that the transceiver module 820 is configured to sendthe data processing indication information to the terminal specificallyincludes: sending the data processing indication information to theterminal according to a locally configured or preconfigured policy.

In one embodiment, the transceiver module 820 is further configured toreceive a trigger message from the first server, where the triggermessage is used to instruct the control function entity to performserver switching for the terminal.

Correspondingly, that the determining module 810 is configured todetermine the second server specifically includes: determine the secondserver based on the trigger message.

It should be understood that the server switching apparatus 800according to this embodiment of this application may be corresponding tothe method on the control function entity side in the foregoing methodembodiment, and the foregoing and other management operations and/orfunctions of the modules in the apparatus 800 are intended to implementcorresponding operations of the method on the control function entityside in the foregoing method embodiment, and therefore can alsoimplement beneficial effects in the foregoing method embodiment. Forbrevity, details are not described herein.

It should be further understood that in this embodiment, the serverswitching apparatus 800 is presented in a form of a functional module.The “module” herein may be an application-specific integrated circuitASIC, a circuit, a processor and a memory that execute one or moresoftware or firmware programs, an integrated logic circuit, and/oranother component that can provide the foregoing functions. In a simpleembodiment, a person skilled in the art may figure out that the serverswitching apparatus 800 may be in a form shown in FIG. 3. Thedetermining module 810 may be implemented by the processor 301 and thememory 302 shown in FIG. 3. The transceiver module 820 may beimplemented by the transceiver 303 shown in FIG. 3. Specifically, aprocessor is implemented by executing a computer program stored in amemory. In one embodiment, when the apparatus 800 is the chip, afunction and/or an implementation process of the transceiver module 820may alternatively be implemented by a pin, a circuit, or the like. Inone embodiment, the memory is a storage unit in the chip, for example, aregister or a cache. The storage unit may alternatively be a storageunit, such as the memory 302 shown in FIG. 3, that is in the computerdevice and that is located outside the chip. A person of ordinary skillin the art may be aware that, in combination with the examples describedin the embodiments disclosed in this specification, units and algorithmoperations may be implemented by electronic hardware or a combination ofcomputer software and electronic hardware. Whether the functions areperformed by hardware or software depends on particular applications anddesign constraint conditions of the technical solutions. A personskilled in the art may use different methods to implement the describedfunctions for each particular application, but it should not beconsidered that the implementation goes beyond the scope of thisapplication.

FIG. 9 is a schematic structural diagram of a server switching apparatus900 according to another embodiment of this application. In oneembodiment, a specific form of the apparatus 900 may be ageneral-purpose computer device or a chip in the general-purposecomputer device. This is not limited in this embodiment of thisapplication. The apparatus 900 is applied to a process in which aterminal is switched from a first server to a second server. Theapparatus 900 is the second server, and the apparatus 900 includes:

a transceiver module 910, configured to receive service data from theterminal; where

the transceiver module 910 is further configured to send data processingindication information to the terminal based on a reception status ofthe service data, and the data processing indication information is usedto instruct the terminal to release a connection to the first server.

It should be understood that the server switching apparatus 900according to this embodiment of this application may be corresponding tothe method on the second server side in the foregoing method embodiment,and the foregoing and other management operations and/or functions ofthe modules in the apparatus 900 are intended to implement correspondingoperations of the method on the second server side in the foregoingmethod embodiment, and therefore can also implement beneficial effectsin the foregoing method embodiment. For brevity, details are notdescribed herein.

It should be further understood that in this embodiment, the serverswitching apparatus 900 is presented in a form of a functional module.The “module” herein may be an application-specific integrated circuitASIC, a circuit, a processor and a memory that execute one or moresoftware or firmware programs, an integrated logic circuit, and/oranother component that can provide the foregoing functions. In a simpleembodiment, a person skilled in the art may figure out that the serverswitching apparatus 900 may be in a form shown in FIG. 3. Thetransceiver module 910 may be implemented by the transceiver 303 shownin FIG. 3. Specifically, a processor is implemented by executing acomputer program stored in a memory. In one embodiment, when theapparatus 900 is the chip, a function and/or an implementation processof the transceiver module 910 may alternatively be implemented by a pin,a circuit, or the like. In one embodiment, the memory is a storage unitin the chip, for example, a register or a cache. The storage unit mayalternatively be a storage unit, such as the memory 302 shown in FIG. 3,that is in the computer device and that is located outside the chip. Aperson of ordinary skill in the art may be aware that, in combinationwith the examples described in the embodiments disclosed in thisspecification, units and algorithm operations may be implemented byelectronic hardware or a combination of computer software and electronichardware. Whether the functions are performed by hardware or softwaredepends on particular applications and design constraint conditions ofthe technical solutions. A person skilled in the art may use differentmethods to implement the described functions for each particularapplication, but it should not be considered that the implementationgoes beyond the scope of this application.

FIG. 10 is a schematic structural diagram of a server switchingapparatus 1000 according to still another embodiment of thisapplication. In one embodiment, the apparatus 1000 may be a terminal, ormay be a chip in the terminal. This is not limited in this embodiment ofthis application. As shown in FIG. 10, the apparatus 1000 includes:

a transceiver module 1010, configured to: receive a first notificationmessage, where the first notification message includes an address of thesecond server; and send to-be-sent service data to the first server andthe second server based on the first notification message; where

the transceiver module 1010 is further configured to receive downlinkdata from the first server;

the transceiver module 1010 is further configured to: obtain dataprocessing indication information; and when obtaining the dataprocessing indication information, send the to-be-sent service data tothe second server; and

the transceiver module 1010 is further configured to receive downlinkdata from the second server.

In one embodiment, the apparatus 1000 further includes a processingmodule 1020, configured to: when the data processing indicationinformation is obtained, stop sending the to-be-sent service data to thefirst server.

In one embodiment, when obtaining the data processing indicationinformation, the transceiver module 1010 is further configured to: senda disconnection message to the first server, where the disconnectionmessage is used to instruct the first server to no longer send downlinkdata to the terminal.

In one embodiment, that the transceiver module 1010 is configured toreceive the first notification message specifically includes: receivingthe first notification message from a control function entity, where thefirst notification message further includes duration of a timer.Correspondingly, that the transceiver module 1010 is configured toobtain the data processing indication information specifically includes:obtaining the data processing indication information based on the firstnotification message, where the data processing indication informationis used to indicate that the duration of the timer elapses.

In one embodiment, that the transceiver module 1010 is configured toobtain the data processing indication information specifically includes:receiving the data processing indication information from a controlfunction entity.

In one embodiment, that the transceiver module 1010 is configured toobtain the data processing indication information specifically includes:receiving the data processing indication information from the secondserver.

It should be understood that the apparatus 1000 according to thisembodiment of this application may be corresponding to the method on theterminal side in the foregoing method embodiment, and the foregoing andother management operations and/or functions of the modules in theapparatus 1000 are intended to implement corresponding operations of themethod on the terminal side in the foregoing method embodiment, andtherefore can also implement beneficial effects in the foregoing methodembodiment. For brevity, details are not described herein.

It should be further understood that in this embodiment, the apparatus1000 is presented in a form of a functional module. The “module” hereinmay be an application-specific integrated circuit ASIC, a circuit, aprocessor and a memory that execute one or more software or firmwareprograms, an integrated logic circuit, and/or another component that canprovide the foregoing functions. In a simple embodiment, a personskilled in the art may figure out that the apparatus 1000 may be a formshown in FIG. 3. The processing module 1020 may be implemented by theprocessor 301 and the memory 302 shown in FIG. 3. The transceiver module1010 may be implemented by the transceiver 303 shown in FIG. 3.Specifically, a processor is implemented by executing a computer programstored in a memory. In one embodiment, when the apparatus 1000 is thechip, a function and/or an implementation process of the transceivermodule 1010 may alternatively be implemented by a pin, a circuit, or thelike. In one embodiment, the memory is a storage unit in the chip, forexample, a register or a cache. The storage unit may alternatively be astorage unit, such as the memory 302 shown in FIG. 3, that is in theterminal and that is located outside the chip. A person of ordinaryskill in the art may be aware that, in combination with the examplesdescribed in the embodiments disclosed in this specification, units andalgorithm operations may be implemented by electronic hardware or acombination of computer software and electronic hardware. Whether thefunctions are performed by hardware or software depends on particularapplications and design constraint conditions of the technicalsolutions. A person skilled in the art may use different methods toimplement the described functions for each particular application, butit should not be considered that the implementation goes beyond thescope of this application.

Unless otherwise specified, an expression used in this applicationsimilar to an expression that “an item includes at least one of thefollowing: A, B, and C” usually means that the item may be any one ofthe following cases: A; B; C; A and B; A and C; B and C; A, B, and C; Aand A; A, A, and A; A, A, and B; A, A, and C; A, B, and B; A, C, and C;B and B; B, B and B; B, B and C; C and C; C, C, and C; and othercombinations of A, B and C. The foregoing uses three elements A, B, andC as an example to describe an optional case of the item. When theexpression is “the item includes at least one of the following: A, B, .. . , and X”, in other words, more elements are included in theexpression, a case to which the item is applicable may also be obtainedaccording to the foregoing rule.

It should be further understood that sequence numbers of the foregoingprocesses do not mean execution sequences in various embodiments of thisapplication. The execution sequences of the processes should bedetermined according to functions and internal logic of the processes,and should not be construed as any limitation on the implementationprocesses of the embodiments of this application.

A person of ordinary skill in the art may be aware that, in combinationwith the examples described in the embodiments disclosed in thisspecification, units and algorithm operations may be implemented byelectronic hardware or a combination of computer software and electronichardware. Whether the functions are performed by hardware or softwaredepends on particular applications and design constraint conditions ofthe technical solutions. A person skilled in the art may use differentmethods to implement the described functions for each particularapplication, but it should not be considered that the implementationgoes beyond the scope of this application.

It may be clearly understood by a person skilled in the art that, forconvenient and brief description, for a detailed working process of theforegoing system, apparatus, and unit, refer to a corresponding processin the foregoing method embodiments, and details are not describedherein again.

In the several embodiments provided in this application, it should beunderstood that the disclosed system, apparatus, and method may beimplemented in other manners. For example, the described apparatusembodiments are merely examples. For example, division into the units ismerely logical function division and may be other division in actualimplementation. For example, a plurality of units or components may becombined or integrated into another system, or some features may beignored or not be performed. In addition, the displayed or discussedmutual couplings or direct couplings or communication connections may beimplemented by using some interfaces. The indirect couplings orcommunication connections between the apparatuses or units may beimplemented in electrical, mechanical, or other forms.

The units described as separate parts may or may not be physicallyseparate, and parts displayed as units may or may not be physical units,may be located in one position, or may be distributed on a plurality ofnetwork units. Some or all of the units may be selected based on actualrequirements to achieve the objectives of the solutions of theembodiments.

In addition, functional units in the embodiments of this application maybe integrated into one processing unit, or each of the units may existalone physically, or two or more units are integrated into one unit.

When the functions are implemented in the form of a software functionalunit and sold or used as an independent product, the functions may bestored in a computer-readable storage medium. Based on such anunderstanding, the technical solutions of this application essentially,or the part contributing to the prior art, or some of the technicalsolutions may be implemented in a form of a software product. Thecomputer software product is stored in a storage medium, and includesinstructions for instructing a computer device (which may be a personalcomputer, a server, a network device, or the like) to perform all orsome of the operations of the methods described in the embodiments ofthis application. The foregoing storage medium includes: any medium thatcan store program code, such as a USB flash drive, a removable harddisk, a read-only memory ROM, a random access memory RAM, a magneticdisk, or an optical disc.

The foregoing descriptions are merely specific implementations of thisapplication, but are not intended to limit the protection scope of thisapplication. Any variation or replacement readily figured out by aperson skilled in the art within the technical scope disclosed in thisapplication shall fall within the protection scope of this application.Therefore, the protection scope of this application shall be subject tothe protection scope of the claims.

What is claimed is:
 1. A communications system, comprising: a controlfunction entity, configured to determine a second server; and send afirst notification message to a terminal, the first notification messagecomprises an address of the second server, and the first notificationmessage instructing the terminal to send service data to a first serverand the second server; and the second server, configured to receive theservice data from the terminal; send a second notification message tothe control function entity based on a reception status of the servicedata; the control function entity, further configured to send dataprocessing indication information to the terminal when an amount ofuplink data from the terminal to the second server has satisfied apredefined condition, the data processing indication informationinstructs the terminal to release a connection to the first server; andthe second server, further configured to send downlink data to theterminal.
 2. The communications system according to claim 1, wherein thecontrol function entity is further configured to: receive a triggermessage from the first server, the trigger message instructs the controlfunction entity to perform server switching for the terminal; anddetermine the second server based on the trigger message.
 3. Thecommunications system according to claim 1, the control function entityis further configured to determine the second server based on at leastone of: location information of the terminal, information about agateway to which the terminal belongs, network information, or serverload information.
 4. The communications system according to claim 1,wherein the second server is further configured to determine the amountof uplink data on the second server that comes from the terminal hassatisfied the predefined condition.
 5. The communications systemaccording to claim 1, wherein the first notification message includes aduration of a timer, wherein the duration of the timer indicates aduration of time elapse after which the terminal is to send the servicedata to the second server.
 6. The communications system according toclaim 1, wherein the data processing indication information indicatesthat the second server is capable of controlling the terminal.
 7. Aserver switching method, the method comprising: determining, by acontrol function entity, a second server; sending, by the controlfunction entity, a first notification message to a terminal, wherein thefirst notification message comprises an address of the second server,and the first notification message instructs the terminal to sendservice data to a first server and the second server; receiving, by thesecond server, service data from the terminal; sending, by the secondserver, a second notification message to the control function entitybased on a reception status of the service data; and sending, by thecontrol function entity, data processing indication information to theterminal when an amount of uplink data from the terminal to the secondserver has satisfied a predefined condition, wherein the data processingindication information instructs the terminal to release a connection tothe first server.
 8. The server switching method according to claim 7,further comprising: receiving, by the control function entity, a triggermessage from the first server, wherein the trigger message instructs thecontrol function entity to perform server switching for the terminal;and determining the second server based on the trigger message.
 9. Theserver switching method according to claim 7, further comprising:determining, by the second server, based on at least one of: locationinformation of the terminal, information about a gateway to which theterminal belongs, network information, or server load information. 10.The server switching method according to claim 7, further comprising:determining, by the second server, the amount of uplink data on thesecond server that comes from the terminal has satisfied the predefinedcondition.
 11. A control function entity, comprising: at least oneprocessor, and a memory storing computer-executable instructions, whichwhen executed by the at least one processor, cause the control functionentity to: determine a second server; send a first notification messageto a terminal, wherein the first notification message comprises anaddress of the second server, and the first notification messageinstructs the terminal to send service data to a first server and thesecond server; receive, by the control function entity, a secondnotification message from the second server; and send, by the controlfunction entity, data processing indication information to the terminalwhen an amount of uplink data from the terminal to the second server hassatisfied a predefined condition, wherein the data processing indicationinformation instructs the terminal to release a connection to the firstserver.
 12. The control function entity according to claim 11, whereinthe sending, by the control function entity, data processing indicationinformation to the terminal comprises: sending, by the control functionentity, the data processing indication information to the terminal basedon the second notification message from the second server.
 13. Thecontrol function entity according to claim 11, wherein thecomputer-executable instructions instruct the control function entityto: send the data processing indication information to the terminalaccording to a locally configured or preconfigured policy.
 14. Thecontrol function entity according to claim 11, wherein thecomputer-executable instructions instruct the control function entityto: receive a trigger message from the first server, wherein the triggermessage instructs to perform server switching for the terminal; anddetermine the second server based on the trigger message.
 15. Thecontrol function entity according to claim 11, wherein thecomputer-executable instructions instruct the control function entityto: determine the second server based on at least one of: locationinformation of the terminal, information about a gateway to which theterminal belongs, network information, or server load information.
 16. Aserver switching method, the method comprising: determining, by acontrol function entity, a second server; sending, by the controlfunction entity, a first notification message to a terminal, wherein thefirst notification message comprises an address of the second server,and the first notification message instructs the terminal to sendservice data to a first server and the second server; receiving, by thecontrol function entity from the second server, a second notificationmessage, wherein the second notification message is sent based on areception status of the service data; and sending, by the controlfunction entity, data processing indication information to the terminalwhen an amount of uplink data from the terminal to the second server hassatisfied a predefined condition, wherein the data processing indicationinformation instructs the terminal to release a connection to the firstserver.
 17. The server switching method according to claim 16, furthercomprising: receiving, by the control function entity, a trigger messagefrom the first server, wherein the trigger message instructs the controlfunction entity to perform server switching for the terminal; anddetermining the second server based on the trigger message.
 18. Theserver switching method according to claim 16, further comprising:determining, by the second server, based on at least one of: locationinformation of the terminal, information about a gateway to which theterminal belongs, network information, or server load information.